Buying a new mattress is a significant purchase, so you need to ensure you get the correct size for your existing bed frame and the space available in your bedroom.
However, not all mattress manufacturers make each size, and some even have non-standard measurements just to confuse you!
We surveyed 10 of the leading organic mattress brands to determine the official standard mattress sizes in the US in 2025.
Using this data, you can measure up before you order. and make sure the mattress you buy is the perfect fit for your space.
The graphic above shows the most commonly occurring sizes across the top 10 organic mattress manufacturers in the US.
Want to know the mattress sizes in feet and inches, or in centimeters? This handy conversion chart gives you the dimensions in whichever format works best for you.
| Inches | Feet / Inches | Centimeters | |
|---|---|---|---|
| Crib | 28” x 52” | 2'4" x 4'4" | 71.1 x 132.1 cm |
| Twin | 38" x 75" | 3'2" x 6'3" | 96.5 x 190.5 cm |
| Twin XL | 38" x 80" | 3'2" x 6'8" | 96.5 x 203.2 cm |
| Full / Double | 54" x 75" | 4'6" x 6'3" | 137.2 x 190.5 cm |
| Full XL | 54" x 80" | 4'6" x 6'8" | 137.2 x 203.2 cm |
| Queen | 60" x 80" | 5' x 6'8" | 152.4 x 203.2 cm |
| King | 76" x 80" | 6'4" x 6'8" | 193 x 203.2 cm |
| California King | 72" x 84" | 6' x 7' | 182.9 x 213.4 cm |
Crib mattress sizes are regulated so that they fit inside a standard crib frame. None of the brands we tested were oversized, so you don’t need to worry about the fit.
The best organic crib mattresses are often dual-sided. They have a firm baby side (suitable for up to 1yo) and a slightly softer toddler side. You can flip the mattress once your baby is ready, so they last longer and offer better value for money.
Measures: 38" x 75" | 3'2" x 6'3" | 96.5 x 190.5 cm
Minimum Room Size: 7’ x 10’
Available At: All manufacturers
The smallest adult mattress size in the US, the twin or single mattress is large enough for a child or a small to medium-sized single adult. However, it doesn’t allow for much excess room to stretch out, while taller adults may find their feet hanging off the end.
It’s best used for kids' bedrooms, bunk beds, or smaller guest rooms where space is limited.
Measures: 38" x 80" | 3'2" x 6'8" | 96.5 x 203.2 cm
Minimum Room Size: 7’ x 11’
Available At: All manufacturers
The Twin XL is the same width as the Twin but is 5 inches longer, which makes a real difference to anyone over 6 feet. It’s perfect for taller adults, students, or teens who have outgrown the Twin but who don’t have space or budget for a larger size.
Measures: 54" x 75" | 4'6" x 6'3" | 137.2 x 190.5 cm
Minimum Room Size: 9’ x 11’
Available At: All manufacturers
A full or double mattress is the smallest size that is potentially suitable for two people to share - although in reality, while it works fine for two smaller people, it can get a bit cramped for space if either sleeper is above average size.
However, it’s quite comfortable for single occupants of all sizes. Although it lacks the extra length of the Twin XL, taller people have enough space to sleep diagonally and can therefore still keep their feet in the bed.
A full bed fits comfortably in most medium-sized bedrooms, allowing space for nightstands and other bedroom furniture.
Measures: 54" x 80" | 4'6" x 6'8" | 137.2 x 203.2 cm
Minimum Room Size: 9’ x 12’
Available At: PlushBeds, My Green Mattress
The Full XL is the same width as the full mattress but with 5 inches extra length. If two people are sharing and one is 6 feet tall or over, the standard full size is often inadequate as the option of sleeping diagonally is removed.
However, two people can share a Full XL even if one is taller, providing both are of medium to narrow build.
Measures: 60" x 80" | 5' x 6'8" | 152.4 x 203.2 cm
Minimum Room Size: 10’ x 12’
Available At: All manufacturers
Queen beds allow individuals and couples of virtually any height and body weight to sleep together in comfort, which explains why it’s America’s most popular mattress size. It’s a happy middle ground of being more spacious than a Full, but cheaper, lighter, and easier to move than a King.
A Queen mattress provides more than enough space for both sleepers to move around without knocking or disturbing the other - provided you have invested in a quality organic mattress with low motion transfer.
Measures: 76" x 80" 6'4" x 6'8" 193 x 203.2 cm
Minimum Room Size: 12’ x 12’
Available At: All manufacturers
If you have enough space in your bedroom and can afford the additional cost, then the King mattress is the ultimate size for couples. It gives both partners plenty of space - with as much width as you would get sleeping alone in a Twin. So there’s no fighting over the middle ground!
They are a popular choice for master bedrooms where space is less of an issue, meaning they fit in comfortably and still leave plenty of room to walk around
Measures: 72" x 84" 6' x 7' 182.9 x 213.4 cm
Minimum Room Size: 11’ x 13’
Available At: All manufacturers
The California or Cal King mattress is slightly narrower than a standard King, but also 4 inches longer. It’s perfect for couples where one or both partners are significantly taller than average.
It’s also suitable for anyone who has pets sleeping on the end of their bed. However, you may need a larger room to accommodate the extra length and still allow space to walk around the foot of the bed.
Often Queen, King & California King mattresses also come in “split” varieties. This is where you buy two separate mattresses that are designed to be pushed together and used on the same bed.
The benefit of this is that it allows each sleeper to customize their own specifications of style and firmness, without needing to move to a separate bed. They also work really well if you have an adjustable bed frame.
When combined, the dimensions of the split mattresses add up to the same as the standard versions. For example, both a King and a Split King (when both halves are combined) measure 76" x 80".
The measurement data above is derived from a survey of 10 of the best-selling organic mattress brands in the US.
Where variations occurred, we took the mode (most frequently occurring) dimensions of each mattress size across our data sample and applied these as the overall industry standard.
In cases where a manufacturer did not make a particular size, it was excluded from the data sample.
The brands surveyed were:
Note: Avocado owns the Brentwood Home brand and both use the same sizes.
A full breakdown of the sizes and range by brand is available below.
Although the majority of mattress brands in our survey conformed to the standard sizes, there were some that did not. Also, some brands did not make particular sizes, while others did.
The following table shows a breakdown of the data we collected by brand. We have highlighted instances where a brand’s dimension differed from the industry standard. Blank cells indicate that a brand does not produce a mattress in that particular size.
| Crib | Twin | Twin XL | Full | Full XL | Queen | King | Cal King | |
|---|---|---|---|---|---|---|---|---|
| Avocado / Brentwood | 28” x 52” | 38" x 75" | 38" x 80" | 54" x 75" | 60" x 80" | 76" x 80" | 72" x 84" | |
| Awara | 38" x 75" | 38" x 80" | 54" x 75" | 60" x 80" | 76" x 80" | 72" x 84" | ||
| Dreamcloud | 38" x 75" | 38" x 80" | 54" x 75" | 60" x 80" | 76" x 80" | 72" x 84" | ||
| Happsy | 38" x 75" | 38" x 80" | 53" x 75" | 60" x 80" | 76" x 80" | 72" x 84" | ||
| Layla | 38" x 75" | 38" x 80" | 54" x 75" | 60" x 80" | 76" x 80" | 72" x 84" | ||
| My Green Mattress | 27 1/4″ x 52″ | 39" x 75" | 39" x 79" | 54" x 75" | 54" x 79" | 60 x 79" | 75" x 79" | 72" x 83" |
| Naturepedic | 27 1/4" x 51 5/8" | 38" x 75" | 38" x 80" | 54" x 75" | 60" x 80" | 76" x 80" | 72" x 84" | |
| Nectar | 38" x 75" | 38" x 80" | 54" x 75" | 60" x 80" | 76" x 80" | 72" x 84" | ||
| PlushBeds | 38" x 75" | 38" x 80" | 54" x 75" | 54" x 80" | 60" x 80" | 76" x 80" | 72" x 84" | |
| Saatva | 28" x 52" | 38" x 75" | 38" x 80" | 54" x 75" | 60" x 80" | 76" x 80" | 72" x 84" |
This guide has focused on mattress dimensions in the US. However, other parts of the world have different standard dimensions and in some cases, use different names as well.
For example, a King mattress in the UK is the same size as a Queen in the US. A King in the US is called a Super King in the UK. While in Europe, most mattresses are sold in specific measurements rather than standard sizes.
If you’re looking to buy a mattress abroad, the following table shows the international variations and how they compare.
| Australia | UK / Ireland | Europe | |
|---|---|---|---|
| Twin (Single) | 36" x 75" | 36" x 75" | 35" x 79" |
| Full (Double) | 54" x 75" | 54" x 75" | 55" x 79" |
| Queen | 60" x 80" | N/A | 63" x 79" |
| King | 72" x 80" | 60" x 78" | 71" x 79" |
| Super King | N/A | 72" x 78" | N/A |
There are several “non-standard” mattress sizes that you may be able to get hold of if none of the above work for you.
However, bear in mind that these sizes generally aren’t available by default, and none of the brands we surveyed carry them. You can always contact your chosen brand to see if you can have them custom-made, but be aware you’ll pay a premium price for a bespoke order.
It’s also worth noting that if you do order one of these sizes, you’ll probably need to get a custom bed frame made as well. You’d also need a larger bedroom to accommodate them comfortably.
You can measure your mattress with an ordinary steel tape measure. Hook the lip at the end of the tape over the midpoint of your mattress, and stretch it in a straight line to the opposite side.
Repeat the process width and lengthways to get your overall dimensions.
The dimensions we have provided in this guide are width x length.
If you are measuring a bed frame to see what size mattress it will accommodate, be sure to take the inside and not the outside measurements (i.e. do not include the width of the frame itself).
If you're buying a new non-toxic bed frame, simply ensure you get the correct size for your mattress and that it fits comfortably in the space available.
You should find that the frame dimensions are slightly larger than the mattress dimensions, this is to allow it to fit inside easily.
Most RV mattresses are standard sizes, with Twin and Queen being the most common.
Many people choose a low profile thin organic mattress for their RV because they are lighter and easier to fold and transport.
Yes, full and double mean the same thing in US bed sizes.
No, putting 2 full beds together would not equal a Queen. The result would be significantly wider and also 5 inches shorter than a standard Queen size.
There is no common or standard mattress height in the US or globally. The height of a mattress will vary depending on the type of mattress and what it is made of. It can also increase if you choose to use an organic mattress topper for extra padding and protection.
Many manufacturers offer a choice of heights on each of their product lines, so you can always find a height that suits your needs.
Queen is the most popular bed size for couples in America in 2025.
The Alaskan King is the largest bed size, but it is rarely sold “off the shelf” and would usually need to be custom ordered.
In terms of readily available standard sizes, the King is the widest and the California King is the longest size available.
